PostgreSQL
PostgreSQL是一個開源的，社區驅動的，符合標準的 對象-關係型 資料庫系統。
本文檔介紹如何安裝PostgreSql。同時，也介紹了如何配置PostgreSql，使遠程客戶端能夠操作之。在某些應用中，PostgreSQL可以代替MySQL作為LAMP網絡棧的一部分。
安裝PostgreSQL[編輯 | 編輯原始碼]
安裝 postgresql包，並為新用戶postgres設置一個密碼 。
[postgres]$作為前置符號。你可以以root用戶執行su - postgres登陸postgres用戶。如果你使用sudo，可以以普通用戶執行sudo -i -u postgres。在PostgreSQL可以正確使用之前，資料庫集群必須被初始化:
# sudo su - postgres -c "initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'"
啟動PostgreSQL，(可選)，添加 PostgreSQL 到daemons列表裡作為守護進程同時啟動：
# systemctl enable postgresql.service # systemctl start postgresql.service
創建第一個資料庫/用戶[編輯 | 編輯原始碼]
以 postgres 用戶身份, 添加一個新的資料庫用戶使用 createuser 命令
[postgres]$ createuser --interactive
輸入要增加的角色名稱: 我登錄 Arch 的用戶名
以具備讀寫權限的用戶身份，創建一個新的資料庫,使用createdb 命令。
從你的 shell (不是 以 postrgres 用戶的身份)
$ createdb myDatabaseName
熟悉PostgreSQL[編輯 | 編輯原始碼]
連接資料庫shell[編輯 | 編輯原始碼]
登陸為postgres用戶，啟動主要資料庫shell psql，你可以創建資料庫或表、設計權限和運行原始的SQL命令。使用-d選項連接你創建的資料庫（如果沒有指定資料庫，psql會嘗試連接與你用戶名同名的資料庫）。
[postgres]$ psql -d myDatabaseName
一些有用的命令：
- 幫助
=> \help
- 連接到資料庫<database>
=> \c <database>
- 列出所有用戶以及他們的權限
=> \du
- 展示當前資料庫中所有的表相關的匯總信息
=> \dt
- 退出psql
=> \q or CTRL+d
當然也有更多元命令，但這些應該能夠幫助您開始。
選擇配置[編輯 | 編輯原始碼]
配置 PostgreSQL 被遠程訪問[編輯 | 編輯原始碼]
PostgreSQL Server 的配置文件是 postgresql.conf。此文件在資料庫數據目錄中，通常在 /var/lib/postgres/data。這個目錄也包含其他主要的配置文件，包括 pg_hba.conf。
find 或 locate 沒有找到這些配置文件的原因。編輯文件/var/lib/postgres/data/postgresql.conf。在connections and authentications選項中，按照你的需要添加listen_addresses行:
listen_addresses = 'localhost,my_remote_server_ip_address'
仔細檢查其他行。
/var/lib/postgres/data/pg_hba.conf配置基於主機的認證。這個文件控制哪些主機允許連接。要注意默認情況下允許所有本地用戶連接任何資料庫用戶，包括資料庫的超級用戶。根據下面的描述添加一行:
# IPv4 local connections: host all all my_remote_client_ip_address/32 md5
my_remote_client_ip_address是客戶端的IP位址。
如需更多幫助請查看pg_hba.conf的文檔。
在完成編輯後你需要重啟 postgresql.service服務使你的配置生效。
5432埠作為遠程連接。確保打開這個埠並可以接受入口連接如果遇到麻煩，使用下面的命令查看伺服器日誌:
# journalctl -u postgresql
Configure PostgreSQL to work with PHP[編輯 | 編輯原始碼]
Install the PHP-PostgreSQL modules php-pgsql包.
Edit the file /etc/php/php.ini. Find the line that starts with:
;extension=pgsql.so
Change it to:
extension=pgsql.so
If you need PDO, do the same thing with ;extension=pdo.so and ;extension=pdo_pgsql.so. If these lines are not present, add them. These lines may be in the "Dynamic Extensions" section of the file, or toward the very end of the file.
Restart the Apache web server:
- systemctl restart httpd
Change default data dir (optional)[編輯 | 編輯原始碼]
The default directory where all your newly created databases will be stored is /var/lib/postgres/data. To change this, follow these steps:
Create the new directory and assign it to user postgres (you eventually have to become root):
mkdir -p /pathto/pgroot/data chown -R postgres:postgres /pathto/pgroot
Become the postgres user(change to root, then postgres user), and initialize the new cluster:
initdb -D /pathto/pgroot/data
If not using systemd, edit /etc/conf.d/postgresql and change the PGROOT variable(optionally PGLOG) to point to your new pgroot directory:
#PGROOT="/var/lib/postgres/" PGROOT="/pathto/pgroot/"
If using systemd, edit /etc/systemd/system/multi-user.target.wants/postgresql.service, which links to /usr/lib/systemd/system/postgresql.service, and change the default PGROOT path.
#Environment=PGROOT=/var/lib/postgres/ Environment=PGROOT=/pathto/pgroot/
You will also need to change the default PIDFile path.
PIDFile=/pathto/pgroot/data/postmaster.pid
Change default encoding of new databases to UTF-8[編輯 | 編輯原始碼]
When creating a new database (e.g. with createdb blog) PostgreSQL actually copies a template database. There are two predefined templates: template0 is vanilla, while template1 is meant as an on-site template changeable by the administrator and is used by default. In order to change the encoding of new database, one of the options is to change on-site template1. To do this, log into PostgresSQL shell (psql) and execute the following:
First, we need to drop template1. Templates cannot be dropped, so we first modify it so it is an ordinary database:
UPDATE pg_database SET datistemplate = FALSE WHERE datname = 'template1';
Now we can drop it:
DROP DATABASE template1;
The next step is to create a new database from template0, with a new default encoding:
CREATE DATABASE template1 WITH TEMPLATE = template0 ENCODING = 'UNICODE';
Now modify template1 so it is actually a template:
UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template1';
(OPTIONAL) If you do not want anyone connecting to this template, set datallowconn to FALSE:
UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
pg_upgrade.Now you can create a new database by running from regular shell:
su - su - postgres createdb blog;
If you log in back to psql and check the databases, you should see the proper encoding of your new database:
\l
returns
List of databases
Name | Owner | Encoding | Collation | Ctype | Access privileges
-----------+----------+-----------+-----------+-------+----------------------
blog | postgres | UTF8 | C | C |
postgres | postgres | SQL_ASCII | C | C |
template0 | postgres | SQL_ASCII | C | C | =c/postgres
: postgres=CTc/postgres
template1 | postgres | UTF8 | C | C |
管理工具[編輯 | 編輯原始碼]
- phpPgAdmin — Web-based administration tool for PostgreSQL.
- pgAdmin — GUI-based administration tool for PostgreSQL.
Postgresql升級配置[編輯 | 編輯原始碼]
快速指南[編輯 | 編輯原始碼]
This is for upgrading from 9.2 to 9.3.
pacman -S --needed postgresql-old-upgrade su - su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/data-9.2' su - postgres -c 'mkdir /var/lib/postgres/data' su - postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'
If you had custom settings in configuration files like pg_hba.conf and postgresql.conf, merge them into the new ones. Then:
su - postgres -c 'pg_upgrade -b /opt/pgsql-9.2/bin/ -B /usr/bin/ -d /var/lib/postgres/data-9.2 -D /var/lib/postgres/data'
If the "pg_upgrade" step fails with:
- cannot write to log file pg_upgrade_internal.log
Failure, exiting
Make sure you're in a directory that the "postgres" user has enough rights to write the log file to (/tmpfor example). Or use "su - postgres" instead of "sudo -u postgres". - LC_COLLATE error that says that old and new values are different
Figure out what the old locale was, C or en_US.UTF-8 for example, and force it when calling initdb.
sudo -u postgres LC_ALL=C initdb -D /var/lib/postgres/data
- There seems to be a postmaster servicing the old cluster.
Please shutdown that postmaster and try again.
Make sure postgres isn't running. If you still get the error then chances are these an old PID file you need to clear out.
> sudo -u postgres ls -l /var/lib/postgres/data-9.2 total 88 -rw------- 1 postgres postgres 4 Mar 25 2012 PG_VERSION drwx------ 8 postgres postgres 4096 Jul 17 00:36 base drwx------ 2 postgres postgres 4096 Jul 17 00:38 global drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_clog -rw------- 1 postgres postgres 4476 Mar 25 2012 pg_hba.conf -rw------- 1 postgres postgres 1636 Mar 25 2012 pg_ident.conf drwx------ 4 postgres postgres 4096 Mar 25 2012 pg_multixact drwx------ 2 postgres postgres 4096 Jul 17 00:05 pg_notify drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_serial drwx------ 2 postgres postgres 4096 Jul 17 00:53 pg_stat_tmp drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_subtrans drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_tblspc drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_twophase drwx------ 3 postgres postgres 4096 Mar 25 2012 pg_xlog -rw------- 1 postgres postgres 19169 Mar 25 2012 postgresql.conf -rw------- 1 postgres postgres 48 Jul 17 00:05 postmaster.opts -rw------- 1 postgres postgres 80 Jul 17 00:05 postmaster.pid # <-- This is the problem > sudo -u postgres mv /var/lib/postgres/data-9.2/postmaster.pid /tmp
- ERROR: could not access file "$libdir/postgis-2.0": No such file or directory
Retrieve postgis-2.0.so from postgis package for version postgresql 9.2 () and copy it to /opt/pgsql-9.2/lib (make sure the privileges are right)
詳細說明[編輯 | 編輯原始碼]
需要注意的是，這些指令可能會導致數據丟失。 後果自負.
推薦把下面的加入你的 /etc/pacman.conf 文件中:
IgnorePkg = postgresql postgresql-libs
這將確保你不會不小心將資料庫升級到不兼容的版本中。當一個升級可用時，pacman將通知你，因為在pacman.conf中的設置，它跳過了升級。小版本升級 (e.g., 9.0.3 to 9.0.4) 可以被安全地執行。不過，當如果你突然做一個不同的主版本升級時，(e.g., 9.0.X to 9.1.X), 您可能無法訪問你的任何數據。請務必檢查PostgreSQL的主頁 (https://www.postgresql.org/) ，以確認每次升級所需要的步驟。對於為什麼是這種情況見 versioning policy。
主要有兩種方式來升級您的PostgreSQL資料庫。閱讀官方文檔細節。
For those wishing to use pg_upgrade, a postgresql-old-upgrade包 package is available in the repositories that will always run one major version behind the real PostgreSQL package. This can be installed side by side with the new version of PostgreSQL. When you are ready to perform the upgrade, you can do
pacman -Syu postgresql postgresql-libs postgresql-old-upgrade
Note also that the data directory does not change from version to version, so before running pg_upgrade it is necessary to rename your existing data directory and migrate into a new directory. The new database must be initialized by starting the server, as described near the top of this page. The server then needs to be stopped before running pg_upgrade.
# systemctl stop postgresql # su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata' # systemctl start postgresql # systemctl stop postgresql
Reference the upstream pg_upgrade documentation for details.
The upgrade invocation will likely look something like the following (run as the postgres user). Do not run this command blindly without understanding what it does!
# su - postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-8.4/bin/ -B /usr/bin/'
You could also do something like this (after the upgrade and install of postgresql-old-upgrade) (NB: these instructions DO NOT seem to work for 9.2 -> 9.3 upgrades)
# systemctl stop postgresql # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start # pg_dumpall >> old_backup.sql # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop # systemctl start postgresql # psql -f old_backup.sql postgres
Troubleshooting[編輯 | 編輯原始碼]
Improve performance of small transactions[編輯 | 編輯原始碼]
If you are using PostgresSQL on a local machine for development and it seems slow, you could try turning synchronous_commit off in the configuration (/var/lib/postgres/data/postgresql.conf). Beware of the caveats, however.
synchronous_commit = off
空閒時防止磁碟寫入[編輯 | 編輯原始碼]
PostgreSQL periodically updates its internal "statistics" file. By default, this file is stored on disk, which prevents disks spinning down on laptops and causes hard drive seek noise. It's simple and safe to relocate this file to a memory-only file system with the following configuration option:
stats_temp_directory = '/run/postgresql'